The speaker takes a breath of air they call "chemical filled," which suggests pollution, toxicity, or perhaps a harsh, artificial world. Instead of coughing or complaining, they smile. That small choice is the heart of the poem. The title, "live," reads almost like an instruction, or like a quiet decision to keep going.
The last two lines turn things around. The breath makes wilted flowers bloom "in their heart." It's unclear whose heart this is, and that vagueness is part of the charm. It could be the speaker's own, or the hearts of other people. Either way, the flowers are an image of hope or feeling that had faded and now comes back to life. Judging by the imagery, the speaker finds renewal in a place that shouldn't allow it.
The mood is gentle and quietly defiant. It's short and calm, but there's a stubborn optimism underneath, a sense that being alive is worth smiling about even when conditions are bad.